Behavioral Responses of Assamese Macaques (Macaca assamensis) to Variations in Food Availability and Climatic Factors in Longrui, Guangxi, China

Investigating adaptive responses to environmental variables can shed light on how animals survive in a particular environment. We examined changes in the diet and activity budget of Assamese macaques (Macaca assamensis) in a limestone forest in response to variation in food availability and climate. We collected behavioral data via scan sampling from October 2021 to September 2022. Macaques fed on 157 food items obtained from 99 plant species. Macaques were primarily folivorous; their diet comprised five categories of plant foods: young leaves (59% ± SD 20%), mature leaves (7% ± 8%), fruits (30% ± 25%), flowers (4% ± 6%), and stems (1% ± 1%). They consumed more fruits in the rainy season than in the dry season and more young leaves in the dry season than in the rainy season. The consumption of young leaves increased with decreasing temperature and day length, whereas fruit consumption increased when temperature and day length increased. The consumption of mature leaves increased with humidity. The macaques spent most of their time feeding and moving. The proportion of time spent resting was significantly reduced in the rainy season compared with the dry season. The proportion of time spent moving increased with the consumption of flowers and fruits. Moreover, the proportion of time spent moving decreased and the proportion of time spent grooming time increased when temperatures decreased. These results indicated that macaques’ diet and activity budgets change seasonally. They suggest that macaques maximized feeding benefits using a high-cost, high-yield strategy during the rainy season. Conversely, they used a low-cost, low-yield strategy to conserve energy during the dry season. Our findings suggest that Assamese macaques show flexible behavior in response to variation in food availability and weather conditions in a seasonal limestone habitat.